Process for treating the bagasse of sugar cane



stares meals Parser ares- EARNESE GEAR-LE? EEMMER- VALET, 011" 'MEXIGOCITY, MEKIGQ, ASSIGNOR T0 QELU;

LOSE EEMMERVALET, SGGIEDAD ANION 03:? MEXIIGG CITY, MEXICO, A CORPO-RATIGN 0F MEXIQG PROGESSFOE TREATING TEE BAG-ASSE OF SUGAR CANE NoDrawing. Application filed June 8, was, Serial No, 869,525, and inGermany March 23, 192?.

My invention comprises a complete process by which the bagasse of sugarcane may be treated to produce therefrom an excellent grade ofcellulose. My invention is an 1mprovement over that disclosed andclaimed in my Patent No. 1,630,142, dated May 24;, 1927, an applicationfor a reissue of which is now pending. The present application 1s acontinuation in part of United States application Serial No. 192,785,filed May 19, 1927.

Attempts to manufacture cellulose from the bagasse of sugar cane haveheretofore en.-

- tailed considerable expense and have likewise Lil resulted in aproduct that was not readily bleachable except with such strongbleachmoisture content of the bagasse as it-comes from the mill andthereafter separate the longer fibres suitable for cellulose;manufacture from the epidermis, parenchyma, and shorter fibres.

The drying of the bagasse andthe subsequent separation of the fibres ispreferably carried out by the process described and claimed in myco-opending application-Serial No. 366,825 filed May 29, 1929. Thisprocess comprises air drying of the bagasse over a period of one or twoweeks in a building provided with perforated floors and side walls opento the atmosphere, the bagasse being loosely spread about one or two'feet deep on the perforated floors and a' gentle current of air forcedthrou l1 and over the bagasse. The bagasse 1s then "treated preferablyin a hammer-mill which breaks up the hard epidermis into a powdery formand partially opens up the fibrous art to detach the parenchyma andsmaller fi res from the longer fibres. By means of screens and airflotation the longer fibre is then separated from the other parts of thebagasse I and further separation of the smaller fibres The materials arethen ready for chemical 7 treatment by my improved process. In order tomake clear the present process I will describe a treatment of a specificquantity of bagasse fibres togetherwith specific quanti ties of thevarious chemicals to be employed. I wish it understood, however,t hatthe various quantities given are representative only and are not to betaken as limiting my invention except as so limited in my claims. To aquantity of about 300 kilograms of dry bagasse fibre, separated fromother ingredients by the preliminary process above described, I addabout 1200 to 1500 liters of a clear saturated solution of lime. Iheatthe fibres and lime solution together for about one-half hourpreferably first by steam allowed to enter directly into the solution,and then by passage of steam through heating coils, while maintainingthe temperature be-' low the boiling point, referably eta-term peratureof about 90 This treatment of the fibres is of particularvalue as a stepin the elimination of the natural coloring matters and of the sugarcontent, which latter amounts to about one-and one-half to three percent. or evenmore of the weight of the dry bagasse fibres. It isabsolutely essential in order to obtain a good grade of paper stock forthe sugar to be completely eliminated as otherwise it is impossible tobleach to'a. pure white product. After the lime treatment', and whilethe fibres are still immersed in the lime solution I add a cold solutioncontaining sodium sulphite. With the quantities above mentioned I add300 to 500 liters of the sodium ,sulphite solution, the amount of thesulphite in solution bein about onehalf to two per cent. of the fibreweight. Preferably the entire quantity of sodium sulphite amounting toabout one and onehalf to six kilograms, is dissolved in about 100 litersof water, and 200 to 400 liters of water are added coldto the solutionin the cooker to reduce the temperature thereof to sulphite solution,the mixture is now heated matters.

up to the initial temperature by means of steam for about one-half toone hour which time I have found sufiicient for my purposes. I havefound that this treatment of the fibres,

first with clear saturated lime solution and then with the sulphite andlime solution, insures substantially complete elimination of the sugarcontent and also of the natural coloring matters. I believe this to bedue to the partial opening up of the fibre by the alkaline solution topermit the sugars to go into solution and perhaps also to the enhancedsolubility of the sugars in the res ence of lime. The sulphite solution,Thelieve to be of particular value in connection with the elimination ofthe natural coloring After this treatment I draw ofi so much of thesolution as may be readily removed from the fibres, which amounts toabout 1000 liters or two-thirds of the total employed. The fibers arethen washed with addition to the washed fibre of a weak causcaustic ticsolution, comprising about 1,000 liters of otash, caustic soda andsodium or other suitable sulphite in the proportions of about .3 to .6%caustic potash, 3 to 5% caustic soda and to 1 of the sulphite. Themixture is now heated by the addition of live steam in quantitysuflicient to add about 200 liters of water to the solution and thetemperature maintained around 130 C. for from four toeight hours. Thetreatment is .efi'ected in\a closed cooker, the pressure within which isaccordingly raised to about 1 to 2 atmospheres.

The particular proportions of the various chemicals depend upon the ageof the bagasse and also upon the soil in which the sugar cane is grown.In place of the caustic soda additional caustic potash could be used,but this is not preferred on account of the greater expense involved.During this treatment the silica is removed by the caustic poash, thevegetable glue is dissolved, the last traces of the coloring matteraredestroyed, the resinous matter and vegetable iqeaaoa wax are saponifiedoremulsified by the combination of chemicals used, and any epidermis orparenchyma remaining with the fibres has been so acted upon as to renderthem harmless during the further treatment and manufacture of thecellulose. At the end of the cooking process samples of the solution andof the fibre are taken in order to ascertain whether the proper stage ofpurity of the cellulose has been reached, and if it has the pressure isreduced to about one atmosphere and the solution, which I will callsolution B, drawn off "and saved for byproduct manufacture. The fibre isthen washed with hot water or steam until'the water runs practicallyclear. The fibre is then removed from the cooker and placed inhollanders or beaters where it is beaten in a lukewarm solution of about28 C. to 33 C.

of soap preferably of the type of Marseilles soap; about one to threekilograms of the dry soap being in solution in about 1,000 liters ofwater. The material in solution is then heated in the heaters to about507 0 C. The soap solution washes out the last traces of the resins,waxes and gums. This solution is then removed and may, if desired, be

saved for by-product manufacture. The fibre remaining is then thoroughlywashed with lukewarm water having a temperature of 30 C. to 35 C. in thesame heaters and bleached in any well known manner.

I have found it of particular importance that the lime'solutionand thesolution of sulphite added in the initial part of my above describedprocess be added separately wit-1h suiiicient time elapsing before thesulphite solution is added, to insure the full respective effects ofthese reagents. By the separate addition of these solutions I am able toeliminate substantially all of the sugar and coloring matter and henceobtain 'a' cellulose that can be readily bleached without loss ofstrength of the resulting material.

In the latter part of my process it is-of particular importance to addthe soap solution after the removal of the caustic solution and, thesubsequent washing of the fibres. If the soap solution is added whilethe caustic solution is still in the cooker a kind of wax soap is formedwhich adheres in lumps to the cellulose and is most difiicult to. removetherefrom, requiring an immense quantity of hot water, and even afterall this washing the fibres remain slippery to the touch, and aretherefore not readily workable with the usual paper making machinery.

The recouery of by-products is of impor-; tance in my novel process asit substantially lowers the cost thereof. By-products obtainable from myprocess include high grade cellulose from theshort fibres of thebagasse, when these are not added to the longer fibres in the aboveprocess, sweetening syrups, fertilizers, filling material for theplastic arts or aveaaoa for explosives, waxes, resins, glues, etc. Adescription of the various processes by means of which theseby-productsmay be obtained will now be given.

In my above mentioned-'copending application, theseparation of the shortfibres from the parenchyma and epidermis is described.

This separation, briefly, is effected by air flow tation methods tofirst remove the powdered epidermis and dust, followed by screening,

using slit screens through which the shorter fibres pass, leaving theparenchyma behind.- I have found that a very excellent grade ofcellulose, very high in alpha content, may be obtained from theseseparatedshort fibres. According to marketing conditions these may beadded directly to the long fibres and treated therewith by my abovedescribed process or treated separately for by-product manufacture.These shorter. fibres when separated in the above manner are freer fromadhering parenchyma, etc. than are the longer fibres, and I have foundthat they are particularly suitable for the production of a special highgrade of alpha cellulose from which artificial silk of a qualitysuperiorto that hitherto producedmay be manufactured. When treated forthe production of such high grade cellulose, the short fibres are ents.

treated separately by a process similar to that described for the longerfibres. As by my process hereinafter described, I recoversweeteningsyrup from solution A and resins, waxes, glues, etc., fromsolution B, I prefer to use these solutions'intreating the short fibres,inorder to make those solutions as rich as possible in the'recoverableingredi- In treating the short fibres tor the production of artificialsilk, I first use solution A just as it comes from the cooker aftertreatment of the long fibres, and then recondition it by the addition ofclear lime solution and,

after the treatment with this solution add be obtained from exhauststeam of the plant,

I may obtain a b product from the short fibres of considera is strengthand of a very good light color, suitable, without bleaching, fornewspapers or the like or suitable when bleached for other usesoficellulose. It is not essential to use solution A in this case, butits use is preferred in order to enrich the solution with the sugar fromthe fibres...

When using the unconditioned solutions, I agitate the short fibres forfrom four to six hours in solution B, maintain the temperature at aboutC. by exhaust steam of the plant and then wash them, using preferablythe wash water from the longer fibresand finally treat the fibres withthe soap solution, which may also be that used in the treatment of thelonger fibres. I

Vegetable waxes, glues, and resins are precipitated by the use of acidsor in any other known manner from the alkali solution afte its use intreating the fibres.

The parenchyma, separated in the first part of my process from theother-components oi the'bagasse, may be sold without treatment as afiller for explosives, or, if desired, the sugar contents containedtherein may be recovered,

and the remaining material used for other purposes.

The sugars, which amount to about 3% to 5% of the total, may be removedfrom the parenchyma by treatment with so much of solution A with orwithout addition of fresh lime andsulphite solution as is necessary tobring the sugars into solution. This solution is then drawn oil combinedwith all of solution A remaining from the treatment of the long or shortfibres, which solutioncontains the sugars removed from ths fibres andadded to the molasses ofthe sugar plant in such proportions as to reducethe specific gravity to 8 to 12 Be, This miXture'I then pass throughfilter presses, condense the filtrate to about 33 Be, bleaching at thesame time to a crystal clear syrup containing the sugars. This syrupisof value'as a sweetening, material for edible products. It hasa peculiarand pleasant aroma and fiavor,

-'wh ich I believe to be distinctive to my particular process and to thematerials from which it is produced.

The parenchyma, after the above extraction of the sugars, may besoldseparately as filling material for the plastic arts, or may be added tothe separated epidermis and dust and the whole used as a "fertilizer, asmay also be used the filter cakes remaining in the presses afterfiltrationof the sugar containing solution. l have now described mynovel process in considerable detail, and given a re resenta== tivetreatment of a particular quantity of the bagasse. I have described aswell various methods by which each of the constituents of the bagassemay be utilized in by product;

manufacture with a minimum of waste not only or the bagasse but also ofthe various chemicals employed. Certain of the by-prodnets and processesfor their recovery disclosed herein are not claimed in the presentapplication, as they form the subject matter of applications hereinafterto be filed. The particular by-products produced, and consequently thetreatment therefor, will depend to a great extent upon the proximity tothe plant of markets for the products and upon the facilities of theplant for storage, etc. Also the cost of manufacture of chemicals inchemicals are concerned, but giving a poorer all) grade cellulose,whereas at other times it may prove more economical to conditionsolutions A and B in order to produce cellulose for artificial silk.Similarly, in some instances it may be preferable to sell the parenchymawithout treatment, while again, recovery of the sugars therein maybeexpedient.

The cellulose obtained by my improved process is of a particularly finequality. It has a high. alpha rcontent and is readily bleachable to apure white color.

I claim:

1. A-process for treating bagasse fibres which comprises first treatingthe fibres .in a clear saturated solution of lime, later adding theretoa solution containing a suitable sulphite then treating the fibres in asolution containin caustic potash and a suitable sulphite and S11sequently washing the fibres in a soap solution.

2. A process for treating bagasse fibres which comprises first treatingthe fibres in a clear saturated solution of lime, later adding thereto asolution of sodium sulphite, then treating the fibres in a solutioncontaining caustic potash, caustic soda and sodium sulphite andsubsequently washing the fibres in a soap solution. 3. A. process fortreating the bagasse of sugar cane which comprises first separatingepidermis, parenchyma, and, other foreign materials from the fibres,then treating the separated fibres in a clear lime solution and heatingthe same while maintaining the temperature below the boiling point, thenreducing the temperature While adding an alkaline solution containingsulphite ions and again heating to a temperature below the boilingpoint, then removing the solution and thereafter treating the fibreswith a weak alkali solution.

l. A. step in the process for treatin the bagasse of sugar cane whichcomprises ieating bagasse fibres with a clear lime solution to atemperature in the neighborhood of 90 0., then reducing the temperatureto about C. by the addition of cold Water and thereafter adding asolution of sodium sulphite and raising the temperature to its initialvalue.

5. process for treating the bagasse of sugar cane, comprising firstseparating short fibres, epidermis, dust and parenchyma from the longerfibres, then treating the separated moaaea longer fibres in aclearsaturated solution of lime, followed by the addition thereto of asolution of sodium sulphi-te, then removing the solution, washing thefibres and then heating the same in a solution, containing causticpotash, caustic soda and sodium sulphite, then removing the solution andagain washing the fibres, and finally beating the fibres in a heatedsolution of soap.

6. Additional steps in the process according to claim 5 comprisingseparating the shorter fibres from the other material separated from thelonger fibres, then heating the separated short fibres with the-alkalisolution removed after the treatment of the longer fibres, then washingthe shorter fibres moisture content of the bagasse, then mechanicallyseparating the longer fibres from the remainder of the bagasse, treatingthe separated fibres in a clear lime solution to which a solution ofsodium sulphite is added thereafter, then removing the solution from thefibres, washing the fibres and subsequent ly treating the fibres in aweak caustic solution. I

9. A step in the process of treating the ba gasse of sugar cane whichcomprises treat ng separated fibres? of ,bagasse in a clear limesolution while maintaining the temperature below the boiling point ofthe solution, then adding a cold solution of a suitable sulphiteandreheating the mixture to a temperature below the boiling point.

10. The process according to claim 9 wherein the sulphite solution issodium sulphi-te in amount equal to about one-half to two percent of theweight of the bagasse fibres.

In testimony whereof, I have signed my name to this specification.

fifililtl'ifi'l QltfilitES llElvlEs'iliR VALET.

